Signal Head Requirements

Left-turn signal heads are required to have different arrangements as discussed below, depending on the signal face type (shared or separate) and the mode of operation (permissive only, protected only, protected permissive, variable, etc.). These requirements come from the 2011 TMUTCD and are listed below. To see these arrangements detailed graphically, see Table 5-1. It is an unofficial summary of Figures 4D-6 through 4D-12 of the 2011 TMUTCD.
Shared Signal Faces in a Protected-Only Operation:
  • A four-section head with Circular RED, Circular YELLOW, Circular GREEN and left-turn GREEN ARROW is required.
  • Shared signal faces for protected-only operations shall only be used if the Circular GREEN and GREEN ARROW always terminate together (i.e. Split Phasing).
Separate Signal Faces in a Protected-Only Operation:
  • Signal indications for protected-only mode left turns in a separate signal face are required to be a 3 section signal face with RED ARROW, YELLOW ARROW, GREEN ARROW indications.
Shared Signal Faces in a Protected-Permissive Operation:
  • A head with Circular RED, YELLOW, GREEN, as well as YELLOW ARROW, GREEN ARROW is required.
  • Five-section signal faces mounted overhead must be centered over (or slightly right of) a projection of the lane line dividing the through lane and the turn lane.
  • The circular indications must display the same color as the adjacent through indications.
Separate Signal Faces in a Protected-Permissive Operation:
  • A four-section head with steady left-turn RED ARROW, steady left-turn YELLOW ARROW, flashing YELLOW ARROW and steady left-turn GREEN ARROW is required. As a practice, TxDOT does not currently use the dual arrow signal section.
  • The flashing YELLOW ARROW indication is permitted to be displayed while adjacent through signals display a steady circular RED indication.
  • The use of a RED ARROW is required to terminate a steady YELLOW ARROW. Past TxDOT practice to not use RED ARROW indications is now superseded by this new TMUTCD requirement.
Shared Signal Faces in a Permissive-Only Operation:
  • A three-section head with Circular RED, Circular YELLOW, Circular GREEN is required.
Separate Signal Faces in a Permissive-Only Operation:
  • A three-section head with RED ARROW, steady YELLOW ARROW, and flashing YELLOW ARROW is required.
Table 5-1: Left-Turn Signal Head Arrangements
Signal Face Type
Left-Turn Operation
Example of Minimum Required Signal Heads for Left-Turning Lanes
(See TMUTCD Figure Referenced For Details)
Shared
Separate
Protected Only
Protected Permissive
Permissive Only
X
 
X
 
 
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All GREEN heads terminate together.
TMUTCD Figure 4D-9
 
X
X
 
 
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TMUTCD Figure 4D-10
X
 
 
X
 
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Sign is Optional
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Horizontal Option
TMUTCD Figure 4D-11
 
X
 
X
 
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TMUTCD Figure 4D-12
X
 
 
 
X
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TMUTCD Figure 4D-6
 
X
 
 
X
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TMUTCD Figure 4D-7